Paper product



' June 5, 1934. f

G. A. RICHTER ET AL 1,961,914

PAPER PRODUCT Filed Nov. 2l, 1930 Patented June 5, 1934 UNITED STATESPATENT oFFlcE PAPER PRODUCT Application November 21, 1930, Serial No.497,331

11 Claims.

This invention relates to a paper product, and more particularly onewhich is associated with a strength-giving agent, such as regeneratedcellulose, which does not detract appreciably from the absorbency of theproduct. While not restricted thereto, the paper product of the presentinvention is intended more especially for use as towelling or in othersituations where a low-priced sheet material having the quality ofabsorbency, coupled with that of high wet strength, is desired.

When a strength-giving agent, such as regenerated cellulose, isintroduced throughout a waterleaf paper such as intended for use astowelling, for instance in amount as low as 1%, it is found that the wetstrength of such paper may be quadrupled, or even more greatlyincreased, Without detracting appreciably from its absorbency. Inaccordance with the present invention, a paper sheet is produced inwhich the strength-giving agent, and more especially regeneratedcellulose, is non-uniformly distributed depthwise, that is, so that across-section through the paper is made up of layers varying in theircontents of regenerated cellulose. On the accompanying drawing, Figures1 to 5, inclusive, represent enlarged sections through paper productsembodying different forms of our invention, with the appropriate legendsthereon. For instance, the surface portions or outer layers of the papersheet may advantageously contain more regenerated cellulose than its`inner portion or layer, which, in fact, may be entirely devoid ofregenerated cellulose, as illustrated in Figure 1. The resulting sheetas a whole is strong, especially when wet, because of the tough outerlayers; the outer surfaces are resistant toward linting upon abrasion;the inner layer is preserved soft, fluffy, and highly absorbent; and thesheet as a whole has a high capacity for absorbing Water. Such a sheetmay be made as an integral or unitary structure, as by applying viscoseto the surfaces of a waterleaf paper sheet in amount and concentrationonly sufficient to sink into the outer layers of the sheet, fixingregenerated cellulose, as a continuous phase in situ in such layers, asby immersing thev sheet in a solution of a suitablecellulose-regenerating agent, such as boric acid or alum, and finallydrying the sheet. A comparable product may be made from three or moreindependent paper plies, two of these plies containing regeneratedcellulose and being intended as the outer layers of the multi-plyproduct, and the remaining ply or plies lacking regenerated celluloseand being intended as the inner layer or layers of the product, as

illustrated in Figure 2. The plies may be bonded together as throughinterfelting or matting of the contacting surface portions while theyare wet, or through the cementing action'of gelatinized cellulose,freshly-formed regenerated cellulose, or the like. When the greatestsoftness and flexibility are desired in the multi-ply product, as whenit is to be used as towelling, the plies may be superposed Withoutbonding to one another. The tendency in such a multi-ply product for theplies to separate when the towelling is put to use and the difficultiesof cutting, folding, assembling, and laying up into packages may beobviated and coherence of plies may be realized without materialsacrifice of softness and flexibility in the multi-ply product, if theplies are cemented or otherwise united merely locally or at their edges.

In some cases, it is desirable to have the outer plies free from or poorin regenerated cellulose while having the inner ply or plies rich inthis strength-giving agent, as illustrated in Figure 3. This is true ifthe outer plies are to be preserved particulary soft, as is desirablewhen the product is intended as bandage or diaper material. Should it be'an important consideration to produce a product at lower cost, only twoplies may be employed, one of which contains more regeneratedcellulosethan the other, which may, in fact, be devoid of this element,as illustrated in Figure 4.

The principles of the present invention extend tomulti-ply productscomprising one or more exceedingly thin plies made entirely ofregenerated cellulose or Cellophane, for instance a multi-ply productcomprising an inner ply of "Cellophane associated with outer plies ofpaper containing regenerated cellulose or free from regeneratedcellulose, as illustrated in Figure 5. Thus, a product comprising aninner py of Cellophane adhesively united with outer plies of papercontaining about 1% of regenerated cellulose, which paper piles are, ashereinbefore indicated, absorptive, may be of advantage for use as abed-sheet, especially in hospitals, or as a bandage material, as boththese uses call for a sheet material of high wet strength.

By the expression continuous phase of regenerated cellulose as used inthe foregoing description and in the appended claims, we meanregenerated celulose existing as a continuous body, for instance, as apreformed film termed Cellophane, or as an lmpregnant extendingsubstantially uninterruptedly in the surface portions, interior, orthroughout paper. We do not' mean to include thereby an interrupted orlocalized either one or more directions, with regenerated cellulose. asthis means that the impregnated areas will respond differently towetting action than the unimpregnated areas and that the impregnant willimpart to the paper a non-uniform feel, especially in the presence o!water.

What we claim is:

l. A porous paper product possessed of a uniform `feel and containingmore regenerated cellulose es a continuous phase in the pores o! itssur- !aoe portions than in the pores o! its inner portion.

2. A porous paper product possessed of a unitonn feel andcontainingregenerated cellulose n a continuous phase in the -pores ofits surface portions but devoid oi' regenerated cellulose in the poreso! its inner portion.

3. A porous paper product possesed of a uniform reel and containing moreregenerated cel.u loee es a continuous phase in' its inner portion thanin the pores of its surface portions.

4. A porous multi-ply paper possessed oi' a uniform feel and whose pliescontain in their pores at ledit tvo diierent concentrations o!continuous phases o! regenerated cellulose.

5. A multi-ply papel: possessed of a uniform feel and made up of atleest three paper plies, the outer plies containing in their poresregenerated cellulose as continuous phases but the rest of the pliesbeing substantially devoid of regenerated cellulose.`

o. A multi-ply paper of a uniform yimpregnation of paper, as alongspaced lines in feel and made up of at least three paper plies bondedtogether, the outer plies containing in their pores regeneratedcellulose as continuous phases but the rest of the plies beingsubstantialy free from regenerated cellulose.

7. A multi-ply paper possessed of a uniform feel and made up of at leastthree paper plies, the outer plies containing in their pores regeneratedcellulose as continuous phases but the rest of the plies beingsubstantially free from regenerated cellulose, said plies being locallybonded together.

8. A multi-ply paper made up of at least three paper plies. the outerplies containing in their pores regenerated cellulose as continuousphases but the rest of the plies being substantially free fromregenerated cellulose and being bonded together at their edges only.

9.`A multi-,ply product comprising an inner,

` continuous ply of `regenerated cellulose adhesively united to outerabsorptive plies of paper containing in their pores regeneratedcellulose.

l0. A multi-ply product comprising an inner. preformed ply ofregenerated cellulose adhesively united to outer absorptive plies otpaper containing in their pores regenerated cellulose.

`1 1. A multi-ply product comprising an inner, preformedpy ofregenerated cellulose united to outer absorptive plies of papercontaining in their pores about 1 of regenerated cellulose.

GEORGE A. RICHTER. MILTON O. SCHUR.

